Apparatus for producing a pyrolysis product

ABSTRACT

The invention relates to an apparatus for producing a pyrolysis product, the apparatus comprising a pyrolysis reactor for forming pyrolysis product fractions from raw material by fast pyrolysis, a condensing device for condensing gaseous pyrolysis product fractions to mainly liquid pyrolysis product fractions, a combustion boiler arranged in conjunction with the pyrolysis reactor for forming energy fractions, and feeding devices for feeding raw materials to the pyrolysis reactor and the combustion boiler. According to the invention, the apparatus comprises a separating device arranged substantially in conjunction with the pyrolysis reactor for separating other fractions from the gaseous pyrolysis product fractions after the pyrolysis and means for conducting other fractions than the gaseous pyrolysis product fractions from the separator to the combustion boiler.

This application is a Divisional of U.S. patent application Ser. No.12/682,686, filed 9 Jul. 2010, which is a National Stage Application ofPCT/FI2008/050567, filed 10 Oct. 2008, which claims benefit of SerialNo. 20075720, filed 11 Oct. 2007 in Finland and which applications areincorporated herein by reference. To the extent appropriate, a claim ofpriority is made to each of the above disclosed applications.

FIELD OF THE INVENTION

The invention relates to an apparatus defined in the preamble of claim 1for producing a pyrolysis product, the apparatus comprising a pyrolysisreactor for forming pyrolysis product fractions from raw material byfast pyrolysis, a condensing device for condensing gaseous pyrolysisproduct fractions to mainly liquid pyrolysis product fractions, acombustion boiler for forming energy fractions, the pyrolysis reactorbeing arranged in conjunction with the combustion boiler, and feedingdevices for feeding the raw materials to the pyrolysis reactor and thecombustion boiler.

BACKGROUND OF THE INVENTION

It is known from the prior art that a pyrolysis product, i.e. pyrolysisliquid or pyrolysis gas, is produced from different kinds of biomassesor organic materials such as wood, bark, paper, straw, waste plastic,oil shale, lignite, peat or the like by dry distillation with thepyrolysis technique. The pyrolysis is typically performed in oxygen-freeconditions at a temperature of about 300 to 800° C. When slow heatingrate is applied, the pyrolysis liquid, e.g. wood tar from dry wood, cantypically be recovered in an amount of about 20 to 30% by weight. Theamount of the pyrolysis liquid increases when the fast pyrolysis methodis applied. There are many known fast pyrolysis methods for producingpyrolysis products and chemicals.

Fast pyrolysis is typically carried out by heating the fuel to bepyrolyzed in a hot oxygen-free gas flow by introducing the required heatto the pyrolyzer by means of a heating gas, heat exchanger or heattransfer agent, e.g. sand or aluminum oxide based carrier. A bubbling orsand circulating fluidized-bed reactor may be used as the pyrolyzer. Theproduced pyrolysis vapor is condensed to a temperature of less than 150°C. in order to form the pyrolysis liquid.

The fuel to be pyrolyzed, e.g. biomass, may be conducted to a dryerbefore the pyrolyzer for drying in order to reduce the water content ofthe pyrolysis liquid that is being formed. Normally used are the knowndrum, flash or fluidized-bed dryers which typically comprise combustiongas or water vapor as the drying gas. It is also known to use a steamdryer in which the heat is introduced by means of hot sand to the dryeroperating on the fluidized-bed basis and in which only water is removed.The temperature is kept at such level that organic compounds do notescape.

EP publication 513051 (Ensyn Technologies Inc.) describes a method andapparatus for producing a pyrolysis liquid from fuels by fast pyrolysisin such manner that the circulating mass reactor which operates as thepyrolyzer comprises separate mixing and reactor zones. The heat transferto the fuel particles is effected by using heat transporting sand or analumina-silica catalyst having the average particle size of from 40 to500 μm as the heat transfer agent. The method uses an oxygen-freecarrier gas. The feeding material in particle form, oxygen-free carriergas and hot heat-transporting particle material are mixed together inthe base section of the reactor, and the mixture is transported upwardsto a reactor section in which the feeding material is converted toproducts. The contact time between the feed material and the heattransporting material is less than 1.0 seconds. The heat transportingparticle material is separated from the product fractions andrecirculated to the reactor. In the method, the mass ratio of the heattransfer material to the fuel is greater than 5:1.

Also known from prior art is the use of an oxidizing reactor forprocessing sand that exits the pyrolyzer and coke produced during thepyrolysis. In the oxidizing reactor, coke is burned and sand is heatedand recirculated to the pyrolyzer. The ratio of the oxidizing reactorpower to the pyrolyzer fuel power is typically about 1:5. This type ofoxidizing reactor is designed to primarily burn only the coke producedduring the pyrolysis and the non-condensible gases. Therefore, the heatcontent of the coke and non-condensible gases is, by the energy balance,a limiting factor in the mass feed to the pyrolyzer.

A problem with the known pyrolysis processes is the need for additionalfuel in the pyrolyzer and in the additional equipment, such as thedryer, and drifting of the water that has been vaporized in the processto the pyrolysis oil. Normally, the water vaporized for example in thedryer is condensed or conducted to outside air. When the vaporized watercontains organic dry distillation products, application of the processbecomes problematic due to environmental nuisances, e.g. strong odors.Further, the known devices do not permit utilization of differentprocess flows, side flows and unwanted intermediate/end products in theprocess in an efficient manner.

Furthermore, it is previously known from patent FI 117512 by the sameapplicant to integrate the pyrolyzer and the combustion boiler to oneassembly.

OBJECTIVE OF THE INVENTION

The objective of the invention is to eliminate the above-mentionedproblems and to disclose a novel apparatus for use in the production ofa pyrolysis product.

SUMMARY OF THE INVENTION

The apparatus according to the invention is characterized by what hasbeen presented in the claims.

The invention is based on an apparatus for producing a pyrolysis productin a flexible manner. The apparatus comprises a pyrolysis reactor forforming pyrolysis product fractions from a raw material by fastpyrolysis, a condensing device for condensing gaseous pyrolysis productfractions to mainly liquid pyrolysis product fractions, a combustionboiler for forming energy fractions in the form of heat, electricity,steam or gas, the pyrolysis reactor being arranged in conjunction withthe combustion boiler, and feeding devices for feeding the raw materialsto the pyrolysis reactor and the combustion boiler. According to theinvention, the apparatus comprises at least one separating devicearranged substantially in conjunction with the pyrolysis reactor forseparating other product fractions, such as solid and/or liquidfractions, from the gaseous pyrolysis product fractions after thepyrolysis and means for conducting at least part, preferably most, ofthe other fractions than the gaseous pyrolysis product fractions fromthe separator to the combustion boiler.

In this context, the gaseous pyrolysis product fractions may refer tomixtures of gas, steam and/or aerosol.

In one embodiment, the separating device is a cyclone, distiller,decanter, clearing basin, flotation device, centrifuge, other extractoror the like. In one embodiment, an integrated solution is used as theseparating device, in which a combination of the conventional cyclone,impact separator and settling chamber is used for separating the coarsematerial and a fullfeed cyclone, e.g. Cymic, Leka or the like,positioned in the inner tube of the cyclone, is used for separating thefine matter. In one embodiment, a two-phase separating device in whichthe separating cyclones are arranged within each other can be used asthe separating device. Any known separating device suitable for thepurpose may be used as the separating device.

In one embodiment, the apparatus comprises means for feeding the solidscontaining flow or a sub-fraction of that flow, i.e. other than thegaseous fraction flow, that is fed from the separating device to thecombustion boiler, to the pyrolysis reactor, e.g. to its feeding device,after the separating device.

Preferably, the pyrolysis reactor, condensing device and separatingdevice are substantially integrated with the combustion boiler, i.e. anunified assembly is formed, fuel is fed to the combustion boiler andburned in order to produce heat energy, and pyrolysis steam is formedfrom biomass and/or equal organic material containing volatile materialsin the pyrolysis reactor and condensed to pyrolysis liquid in thecondenser, and the heat energy or steam that has been formed in thecombustion boiler is recovered or the heat is circulated to the otherparts of the apparatus, such as to the pyrolysis reactor, e.g. in theform of a hot heat transfer agent. According to the invention, optimumfuel mixtures are fed to the combustion boiler and the pyrolysis reactorin order to improve the efficiency of the combustion and pyrolysis andthe yield of the pyrolysis product, and only part of the heat energythat has been formed in the combustion boiler is conducted to thepyrolysis reactor.

In one embodiment, the quality of the liquid pyrolysis product ismonitored by suitable means. Preferably, the condition that the qualityproperties of the pyrolysis product meet the determined criteria isensured at specific and predetermined intervals, e.g. continuously. Inone embodiment of the invention, the apparatus comprises, in conjunctionwith the condensing device, means for monitoring, preferably in anon-line manner, the water content of the liquid pyrolysis product thathas been condensed by the condensing device. In one embodiment, thewater content of the liquid pyrolysis product is kept below 25%. Forexample, if the water content of the liquid pyrolysis product increases,the temperature of the condensing device may be raised by the adjustingmeans.

In one embodiment of the invention, the apparatus comprises means forconducting non-condensible gas fractions from the condensing device tothe combustion boiler. In one embodiment, the non-condensible gasfractions are conducted from the condensing device to the pipe fittingbetween the separating device and the combustion boiler. In onealternative embodiment, the non-condensible gas fractions are conductedfrom the condensing device directly to the combustion boiler.Preferably, the non-condensible gases, e.g. odorous gases, chemicalcompounds and/or aqueous solution thereof, e.g. from the separator,condenser and/or dryer, are circulated to the combustion boiler to beburned. Alternatively, the non-condensible gases or the like may beconducted to chemical recovery. By blowing, i.e. conducting, thenon-condensible gases to the combustion boiler, it is possible tocontrol e.g. the aerosols which may easily cause problems in theprocess.

In one embodiment of the invention, the apparatus comprises means forfeeding carrier gas to the pyrolysis reactor. In one embodiment, theapparatus comprises means for forming the carrier gas from thecombustion gas of the combustion boiler and circulating it to thepyrolysis reactor. Preferably, water is removed from the combustion gas.The combustion gas may be purified by methods and devices known per se,e.g. electric filter, by means of different types of washers or thelike.

In one embodiment, the carrier gas contains oxygen in an amount of 1 to7% by volume. In a preferred embodiment, the pyrolysis is performed inthe pyrolysis reactor in the presence of oxygen.

In one embodiment, combustion gas, air, water vapor or mixtures thereofare used as the carrier gas.

In a preferred embodiment, the carrier gas is conducted through thepyrolysis reactor without recirculating it to the pyrolysis.

In one embodiment of the invention, the apparatus comprises means forfeeding oxygen, preferably to the carrier gas, for the pyrolysis. In oneembodiment, additional oxygen can be fed to the carrier gas e.g. in theform of air. By increasing the proportion of air, the proportion of theliquefiable components in the pyrolysis product can be altered withrespect to the proportion of the non-condensible fractions, according tothe desired product distribution. The integrated combination of thecombustion boiler and the pyrolysis reactor can thus be used as agasifier-type apparatus.

The stability of the pyrolysis product liquid can be improved by theoxygen included in the carrier gas. When the carrier gas contains e.g. 2to 4% by volume of oxygen, the more reactive compounds react alreadybefore the condensation and the increase of viscosity of the productliquid as a function of time can be reduced. In this manner, thepreservability of the pyrolysis product liquid can be improved, thestorage period can preferably be extended and the competitiveness of theproduct improved.

In one embodiment, the carrier gas may also be used as a circulating gasin the combustion boiler.

In one embodiment, the apparatus comprises means for feeding oxygen tothe combustion boiler.

In one embodiment of the invention, the apparatus comprises at least oneblower, which may be any blower known per se, e.g. a combustion gas orcirculating gas blower, ejector or the like, for feeding thenon-condensible gases and/or combustion gases to the combustion boilerand/or for feeding the carrier gas to the pyrolysis reactor.

In one embodiment of the invention, the apparatus comprises means forrecovering, processing further, circulating in the apparatus and/orutilizing the fractions produced in different parts of the apparatus,such as the product, side and residual fractions. In one embodiment, theapparatus comprises at least one pipe fitting for conducting theselected fraction to the pyrolysis reactor, combustion boiler and/orstorage reservoir.

In one embodiment of the invention, the apparatus comprises means forcirculating at least one side, residual and/or waste flow to thecombustion boiler. In one embodiment, the non-condensible gases from thecondensing device, other fractions than the gaseous product fractionsfrom the separating device, the combustion gas fraction, the refuse flowfrom the raw material feeding to the pyrolysis reactor and the solidsfrom the condensing device can be conducted to the combustion boiler.Preferably, different side, residual and refuse fractions are conductedthrough the combustion boiler.

In one embodiment of the invention, the apparatus comprises means fortransferring the energy-containing product fractions from the combustionboiler to a desired part of the apparatus, e.g. the pyrolysis reactor,dryer, temperature raising and/or recovery. Some of the heat energy thathas been recovered during combustion can be utilized in the pyrolysisreactor e.g. by means of the heat transfer material that is heated inthe combustion boiler. From the combustion boiler, the heated and at thesame time purified heat transfer material is transferred, e.g. at atemperature of 700 to 900° C., to the pyrolysis reactor, so that part ofthe heat energy formed during combustion is transferred to thepyrolysis. The heat energy that is produced during combustion canalternatively be recovered e.g. as steam, electricity or hot water.

In one embodiment of the invention, the apparatus comprises a heattransfer material as the carrier material for transferring theenergy-containing product fractions from the combustion boiler to adesired part of the apparatus, e.g. the pyrolysis reactor or dryer. Inone embodiment, the heat transfer material is in the form of a solid,gas, vapor or liquid. In one preferred embodiment, the heat transfermaterial is selected from the group comprising sand, bed sand, aluminumoxide based material, other fluidization material and the like.

In one embodiment of the invention, the apparatus comprises means forseparating the heat transfer material in a separating device andconducting it to the combustion boiler to be purified and heated. In onepreferred embodiment, other fractions than the gaseous ones which havebeen separated in the separating device contain the heat transfermaterial. The solids-containing flow from the separating device to thecombustion boiler may be controlled by means known per se, e.g. valves.In one embodiment of the invention, the apparatus comprises means forcirculating the heat transfer material from the combustion boiler to thepyrolysis reactor. In one preferred embodiment, circulation of the heattransfer material from the combustion boiler to the pyrolysis reactorand from the pyrolysis reactor back to the combustion boiler through theseparating device has been arranged so that it is integrated inconjunction with the apparatus.

In a preferred embodiment, the same heat transfer material, preferablybed sand, is circulated in the apparatus, at least in the combustionboiler and pyrolysis reactor. Preferably, bed sand operates at the sametime as heat transfer material. In this case, the apparatus comprisesmeans for arranging a shared bed sand circulation. In one embodiment,the apparatus comprises means for conducting the bed sand fraction, i.e.part of the solids-containing flow that has been separated from theseparating device, to the pyrolysis reactor after the separating device,e.g. to the heat transfer material or raw material feed of the reactoror to the feeding device.

The heat transfer material may be fed from the combustion boiler to thepyrolysis reactor through a suitable valve solution known per se, e.g. amechanic, non-mechanic, pressure stop valve, auger valve or L-valve.

In one embodiment, a heat exchanger is arranged between the combustionboiler and the pyrolysis reactor for cooling or heating the heattransfer material to be conducted from the combustion boiler to thepyrolysis reactor.

In one embodiment of the invention, the apparatus comprises means formonitoring and adjusting the temperature of the pyrolysis reactor.Preferably, the temperature of the pyrolysis reactor and the suspensiondensity in the reactor are adjusted by means of the feeding rate of theheat transfer material to be fed, e.g. the amount entering through thefeeding valve, and by means of the temperature of the heat transfermaterial, such as the adjustments of the heat exchanger and thecombustion boiler. For example, if the temperature in the pyrolysisreactor rises, the heat transfer material is cooled or cold heattransfer material is fed at least partly to the pyrolysis reactor e.g.from a separate container or from the flow after the separating device.At the same time, the coke content in the apparatus can be adjusted.

In one embodiment of the invention, the apparatus comprises means forarranging the raw material of the pyrolysis reactor and the carrier gasinto a mixture, preferably a warm mixture. In one preferred embodiment,hot particles of the heat transfer material from the combustion boilerare conducted to the mixture of raw materials and the carrier gas in thepyrolysis reactor. Consequently, an area of heavy turbulence is formedat the mixing point, i.e. a so-called flash effect occurs, whereby thepyrolysis can be initiated rapidly and efficiently. For example, thesand that is used as the heat transfer material is substantially heavierthan the hydrocarbon particles in the raw material of the pyrolysis and,therefore, acceleration of the sand particles induces more efficientheat transfer and mixing of the gases in the mixture flow, resulting inan enhanced pyrolysis.

In one embodiment, the apparatus comprises a dryer in which the fuel tobe pyrolyzed is dried thermically, preferably before the pyrolysis.Preferably, the drier is integrated with the pyrolysis reactor and/orthe combustion boiler, and some of the heat energy that has been formedin the combustion boiler is utilized when drying the fuel to bepyrolyzed. The fuel may be dried e.g. by the hot combustion gases or thehot heat transfer material by utilizing the heat energy of thecombustion boiler. Of course, the drying may also be performed in othermanners. Any dryer known per se, e.g. a low temperature dryer, such as astorage dryer, or the like, can be used as the dryer.

In one embodiment of the invention, the combustion boiler and thepyrolysis reactor are integrated together in such manner that aseparating wall is arranged between them.

Any solid fuel, e.g. forest chips, bark, peat or coal, or a multi-fuelmixture etc. which is burned in order to produce heat energy can be fedto the combustion boiler which is primarily designed for producing heatenergy, such as electricity and steam. In one embodiment, the combustionboiler is provided with heat recovery.

In one preferred embodiment, the apparatus comprises means for adjustingthe feeding to the combustion boiler. Preferably, the capacity of thecombustion boiler is adjusted using the adjustment system of the boileritself on the basis of the fuel feed to the combustion boiler. Thedifferent heat powers of the flows and fractions circulated from thepyrolysis apparatus correspond in magnitude to the power given off bythe bed sand in the pyrolysis process. Therefore, there are nointerferences in the combustion boiler caused by additional flows thatshould be fed thereto.

The fuel to be pyrolysed and fed to the pyrolysis reactor is preferablya wood-containing material, biomass and/or equivalent volatile materialscontaining organic material, e.g. sawdust, straw or waste plastic etc.,which is pyrolyzed to pyrolysis steam in the pyrolysis reactor.

In one embodiment, substantially different raw materials or mixtures ofraw materials are fed to the combustion boiler and the pyrolysisreactor. In one embodiment, at least partly the same raw materials ormixtures of raw materials are fed to the combustion boiler and thepyrolysis reactor.

The most important raw materials for the pyrolysis include residualsfrom the forest industry, such as chips, saw dust and bark chips.However, a high liquid yield is only obtained for dry raw material froma so-called heartwood without bark. In other words, a lesser amount ofthe pyrolysis product is produced from the bark which is furthermoremore unstable and easily phase-separated. Therefore, it is not advisableto feed the same raw material to the pyrolysis reactor and thecombustion boiler. A particularly preferred embodiment is to conductbark-containing raw material to the combustion boiler to produce energyand saw dust to the pyrolysis reactor to produce a pyrolysis liquid. Inaddition, e.g. peat or coal is preferably conducted to the combustionboiler to satisfy the entire fuel need.

In one embodiment, the pyrolysis reactor is a fluidized-bed reactor,bubbling fluidization reactor or the like to which the fluidizationmaterial or the heat transfer material that has been purified and heatedin the combustion boiler and that operates as the fluidization materialcan be conducted with the fuel to be pyrolyzed and with the carrier gas.

In one embodiment, the combustion boiler is a fluidized-bed boiler inwhich fuel and e.g. coke and non-condensible gases are burned and theheat transfer material is heated and purified. The fluidized-bed boilermay be e.g. a bubbling boiler or circulating mass boiler or a variationthereof or other boiler known per se.

The pyrolysis product can be produced by the apparatus according to theinvention with higher efficiency than what is known, because the sideand waste flows which are being produced can be converted in thecombustion boiler to heat or steam for energy production. In theapparatus according to the invention, large quantities of heat energyare being produced as the utilizable product in addition to thepyrolysis product. Part of the heat energy of the combustion boiler isused in the pyrolysis reactor, optionally for drying the fuel to bepyrolyzed, and for combustion of the non-condensible gases in thecombustion boiler, and most of the heat energy is conducted to berecovered e.g. in the form of steam. No additional fuel feed is neededfor the pyrolysis reactor and the optional dryer, the heat energy thatis conducted from the combustion boiler being sufficient for maintainingthe process. On the other hand, the energy content of the solid andcarbon matter, the non-condensible gases and other side flows can beutilized in the method according to the invention by burning themtogether with the other fuels in the combustion boiler. Burning theabove-mentioned waste, flows in the combustion boiler does not have anynegative effect on the operation of the combustion boiler and theproduct efficiency. The water and the non-condensible gases to be fed tothe boiler do not pose problems either in terms of maintaining thenormal temperature of the boiler. Consequently, the waste flow feed tothe combustion boiler does not have to be adjusted separately.

The invention provides the advantage that the solids and non-condensiblegases are not recirculated to the pyrolysis reactor but are insteadprocessed in the combustion boiler. A further advantage is thecirculation of the waste and side flows and in particular combustiblematter to the combustion boiler. After the combustion boiler, theprocess is free of any combustible or contaminated material flows, whichincreases the safety and environmental friendliness of the process. Inthe apparatus according to the invention, mostly all residual flows areconducted through the combustion boiler, so the purification efficiencyis good. Further, the carrier gas is not recirculated to the pyrolysisbut instead to the combustion boiler. Therefore, there will not be anyproblems relating to the contamination of the carrier gas. Consequently,the coke content in the pyrolysis reactor is low, due to the fact thatthe different flows are not directly recirculated to the pyrolysisreactor as in the solutions known from the prior art.

With the apparatus according to the invention, a multistep separatingtechnique can be applied so that good separating efficiency for theunwanted fractions is achieved and wearing of the apparatus can bereduced.

Thanks to the circulation system through the combustion boiler accordingto the invention, the parts of the apparatus, such as the filters, willnot become clogged up. By the invention, it is therefore possible to usea lower process pressure which facilitates the feeding of raw materialsand the heat transfer material.

Furthermore, the solution according to the invention permits controlledshutdown of the reactor. During the shutdown, feeding of the fuel andthe heat transfer material to the pyrolysis reactor can be cut offfirst. In this manner, no interference is provided for the operation ofthe combustion boiler.

LIST OF FIGURES

In the following section, the invention will be described with the aidof detailed exemplary embodiments, referring to the accompanying FIGUREwherein

FIG. 1 presents one embodiment of the apparatus according to theinvention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 presents the apparatus according to the invention for producingpyrolysis products, the apparatus comprising a combustion boiler, i.e. afluidization boiler, 1 for producing heat energy, a fast pyrolysisreactor, i.e. a pyrolyzer, 2 for forming pyrolysis steam, a condensingdevice 3 for condensing the pyrolysis steam, and separate fuel feedingdevices 5 and 6 for feeding raw material to the combustion boiler andthe pyrolyzer. In addition, the apparatus comprises a cyclone 4 forseparating the solids and the heat transfer agent from the pyrolysissteam after the pyrolyzer 2. The fluidization boiler, pyrolyzer,condensing device and cyclone are integrated together in the mannerpresented in the FIGURE. The pyrolyzer is integrated to be inconjunction with the fluidization boiler.

Most of the fuel, e.g. carbon, peat, lignite or oil shale, is fed by thefeeding device 5 to the fluidization boiler 1. Furthermore, the feedingdevice 5 is arranged to feed smaller amounts of forest chips or bark tothe combustion boiler. Also air 22 is fed to the fluidization boiler 1.The feeding device 6 is arranged to feed e.g. wood-containing material,biomass, such as peat, saw dust or straw, or organic material to thepyrolyzer 2.

In the pyrolyzer 2, pyrolysis steam is formed from the fuel to bepyrolyzed by fast pyrolysis at a temperature of 300 to 800° C. In thisdevice embodiment, the pyrolyzer is a circulating mass fluidizationreactor. Heat energy from the fluidization boiler 1 is conducted to thepyrolyzer 2 in the form of hot bed sand through the internal materialcirculation cyclone, sand transfer pipe 9 and L-valve. In thisembodiment, grain size of the bed sand is substantially over 0.5 mm. Aheat exchanger may be fitted to the bed sand transfer pipe 9 in order toadjust the temperature of the sand before the pyrolyzer 2. The sand andthe carbon residue are recirculated to the fluidization boiler 1 fromthe separating device 4.

Solid and carbon matter, such as sand and coke or tar, are separatedfrom the produced pyrolysis steam in the cyclone 4. The separated solidand carbon matter 13 are conducted to the combustion boiler 1 to beburned. Part of the solids, fraction 20, can be conducted to thepyrolyzer 2 through line 9 or alternatively from the pyrolyzer feed. Inthe combustion boiler 1, the bed sand is regenerated and heated andother material flows are burned. The heated sand is recirculated to thepyrolyzer 2.

From the cyclone 4, the pyrolysis steam is conducted to the condensingdevice 3, where the hot pyrolysis steam is condensed and fractionated instages to a pyrolysis product liquid 12. Non-condensible gases, chemicalcompounds and/or aqueous solution thereof are conducted to thefluidization boiler 1 through a circulation pipe 10 to be burned or toan external recovery through a pipe 11. The non-condensible gasfractions, chemical compounds and/or aqueous solution thereof areconducted from the condensing device 3 to the pipe fitting between thecyclone 4 and the combustion boiler 1 where they are mixed with thesolids-based fraction 13, or they are alternatively conducted directlyto the combustion boiler from an ejector 18. The ejector 18 is arrangedto the circulation pipe 10 for blowing the non-condensible gases and/orthe combustion gas fraction 19, circulated from the combustion boiler,to the combustion boiler, if desired. The non-condensible gas fractions,chemical compounds and/or aqueous solution thereof are burned in thefluidization boiler with the other fuels.

In addition, the apparatus may comprise a filter for separating finersolids 21 from the pyrolysis steam.

The combined amount of the solid and carbon matter 13 conducted from thecyclone 4 and the non-condensible gases 10 is substantially less than50% of the total amount of the raw material fed to the combustionboiler.

From the combustion boiler 1, the combustion gas can be conducted to anelectric filter 7. Substantially, the pure combustion gas is circulatedafter the electric filter to the pyrolyzer 2 to serve as the carriergas, to the ejector 18 or it is conducted out from the apparatus 15. Thepure combustion gas 14 is conducted to the heat exchanger 8 where it isheated and water 16 is removed from the gas. From the heat exchanger,the carrier gas 14 which contains about 2 to 6% by volume of oxygen isconducted to the pyrolyzer 2 or the ejector 18 by means of a blower 24.The blower operates in a substantially tar-free atmosphere. Thetemperature of the combustion gas is at this stage about 120° C. Air 17can be added to the carrier gas 14 for increasing the oxygen content ifdesired. The pressure production is utilized in the process. Thepressure of the carrier gas and thereby the pressure of the pyrolysisreactor can be adjusted by the blower 24 and the ejector 18. Thepressure level in the pyrolysis reactor is preferably so adjusted thatat the feed of the pyrolysis reactor, the pressure is close to airpressure in order to avoid feeding problems.

Raw material for the pyrolyzer 2 is mixed with the carrier gas 14. Hotsand from the combustion boiler 1 is conducted to this mixture. Thisresults in a so-called flash effect and the pyrolysis is initiatedefficiently.

The fluidization boiler 1 further comprises a heat recovery device, e.g.a steam recovery/utilization device, a heat exchanger or an internalmaterial circulation cyclone, for recovering the heat energy that hasbeen formed or the heat transfer agent that has been warmed.

The apparatus may comprise a dryer for drying the raw material to bepyrolyzed. The dryer may be integrated to be in conjunction with theapparatus or it may be a separate device. Either the combustion gas ofthe combustion boiler or the sand conducted from the combustion boilermay be utilized as the heat delivering agent in the dryer. Thenon-condensible gases, evaporated water and optional volatilizedchemical compounds and odorous gases are preferably circulated from thedryer to the fluidization boiler to be burned. Any dryer known per se,e.g. a mixing dryer, may be used as the dryer so it is not described inany more detail in this context.

Also, the apparatus may comprise at least one recovery unit forrecovering the chemical compounds separated from different parts of theapparatus for possible subsequent utilization. The chemical compoundsare utilized by means of processes known per se which are not describedin any more detail in this context. The residual and waste flows of therecovery unit may be conducted to the combustion boiler.

By the apparatus according to the invention, the most valuable andsuitable part of the raw material can be used as the material to bepyrolyzed, and the less suitable part in terms of the pyrolysis may befed to the combustion boiler. The raw material may be fractionated byprocesses known per se. For example, the feeding materials to thepyrolyzer 2 may be classified by a classifier known per se, by anoptical separator or in an equivalent manner before the pyrolyzer, andthe so-called refuse fraction 23 can be conducted to the combustionboiler 1.

The apparatus according to the invention is suitable in differentembodiments for producing different kinds of pyrolysis products and forproducing energy fractions, such as heat energy.

The invention is not limited merely to the examples referred to above;instead many variations are possible within the scope of the inventiveidea defined by the claims.

1. An apparatus for producing a pyrolysis product, the apparatuscomprising a pyrolysis reactor for forming pyrolysis product fractionsfrom raw material by fast pyrolysis, a condensing device for condensinggaseous pyrolysis product fractions to mainly liquid pyrolysis productfractions, a combustion boiler for forming energy product fractions, thepyrolysis reactor being arranged in conjunction with the combustionboiler, means for circulating the heat transfer material that is heatedin the combustion boiler from the combustion boiler to the pyrolysisreactor, feeding devices for feeding raw materials to the pyrolysisreactor and the combustion boiler, and means for feeding carrier gas tothe pyrolysis reactor, wherein the apparatus comprises means for feedingthe carrier gas including oxygen to the pyrolysis reactor for performingthe pyrolysis in the pyrolysis reactor in the presence of oxygen inorder to improve stability of the liquid pyrolysis product.
 2. Theapparatus according to claim 1, wherein the apparatus comprises meansfor adding oxygen to the carrier gas for increasing the oxygen contentof the carrier gas.
 3. The apparatus according to claim 1, wherein theapparatus comprises means for forming the carrier gas which containsoxygen from the combustion gas of the combustion boiler and means forcirculating the carrier gas to the pyrolysis reactor.
 4. The apparatusaccording to claim 3, wherein the apparatus comprises a device forpurifying the combustion gas.
 5. The apparatus according to claim 1,wherein the carrier gas contains oxygen in an amount of 1 to 7% byvolume.
 6. The apparatus according to claim 1, wherein the apparatuscomprises a separating device for separating other fractions thangaseous pyrolysis product fractions from the gaseous pyrolysis productfractions after the pyrolysis.
 7. The apparatus according to claim 1,wherein the apparatus comprises means for conducting the solidscontaining flow including solids and heat transfer material from theseparating device to the combustion boiler.
 8. The apparatus accordingto claim 1, wherein the apparatus comprises means for mixing the rawmaterial of the pyrolysis reactor with the carrier gas to form a mixtureand means for conducting the heated heat transfer material from thecombustion boiler to the mixture of the raw material of the pyrolysisreactor and the carrier gas in the pyrolysis reactor.
 9. The apparatusaccording to claim 1, wherein the heat transfer material is selectedfrom the group comprising sand, bed sand, aluminum oxide based material,other fluidization material or the like
 10. The apparatus according toclaim 1, wherein the heat transfer material is bed sand.
 11. Theapparatus according to claim 1, wherein the apparatus comprises a heatexchanger for adjusting the temperature of the heat transfer materialbefore the pyrolysis reactor.
 12. The apparatus according to claim 1,wherein the feeding device is arranged to feed raw materials selectedfrom the group comprising a wood-containing material, residuals from theforest industry and/or biomass to the pyrolysis reactor.
 13. Theapparatus according to claim 1, wherein the feeding device is arrangedto feed raw materials selected from the group comprising residuals fromthe forest industry, bark-containing material, peat, coal, lignite, oilshale and a multi-fuel mixture to the combustion boiler.
 14. A methodfor producing a pyrolysis product, the method comprising feeding rawmaterials to a pyrolysis reactor and a combustion boiler, the pyrolysisreactor being arranged in conjunction with the combustion boiler,forming pyrolysis product fractions from raw material by fast pyrolysisin the pyrolysis reactor, condensing gaseous pyrolysis product fractionsto mainly liquid pyrolysis product fractions, forming energy productfractions in the combustion boiler, heating heat transfer material inthe combustion boiler and circulating the heat transfer material fromthe combustion boiler to the pyrolysis reactor, and feeding carrier gasto the pyrolysis reactor, wherein the method comprises feeding thecarrier gas including oxygen to the pyrolysis reactor and performing thepyrolysis in the pyrolysis reactor in the presence of oxygen in order toimprove stability of the liquid pyrolysis product.
 15. The methodaccording to claim 14, wherein the method comprises adding oxygen to thecarrier gas for increasing the oxygen content of the carrier gas. 16.The method according to claim 14, wherein the method comprises formingthe carrier gas which contains oxygen from the combustion gas of thecombustion boiler and circulating it to the pyrolysis reactor.
 17. Themethod according to claim 14, wherein the carrier gas contains oxygen inan amount of 1 to 7% by volume.
 18. The method according to claim 14,wherein the method comprises mixing the raw material of the pyrolysisreactor with the carrier gas to form a mixture and conducting the heatedheat transfer material from the combustion boiler to the mixture of theraw material of the pyrolysis reactor and the carrier gas in thepyrolysis reactor.